This invention relates to a lens stop auxilairy brake control device in an automatic exposure camera of lens stop value control type.
An automatic exposure camera of lens stop control type is known in the art in which while the lens is being stopped from its fully open state, the light from the object to be photographed, which has passed through the aperture of the lens stop, is measured, and when the lens is stopped to a value suitable for a predetermined shutter speed T.sub.V and a film sensitivity S.sub.V the lens stopping operation is suspended thereby automatically determining the aperture of the lens stop. If in this conventional camera the lens stopping operation is effected with the lens only, then the operating period of time required for stopping the lens from its fully open state is too short to accurately lock the lens stop. Therefore, a slow speed mechanism is provided in association with an operating member actuated by the lens stopping operation.
However, in general, the amount of movement of the lens stop release plate is small with respect to a lens stop value on the minimum lens stop value side. Therefore, even if such a slow speed mechansim as to move the lens stop release plate at an approximately constant speed is employed, the quantity of light is abruptly changed in the vicinity of the minimum lens stop value. Accordingly, when the lens stop releases plate is moved at an approximately constant speed, it is necessary to make the period of time required for stopping the lens from its fully open state sufficiently long. Otherwise, time per exposure value E.sub.V becomes extremely short, and therefore it is difficult to precisely control the lens stopping operation. However, if the entire operating time is made sufficiently long, then the period of time of from the camera release to the shutter operation start is increased, which leads to a delay in exposure. Furthermore, in some cameras the travelling of the lens stop release plate is abruptly changed, and in some cameras it is not so changed. Thus, depending of the type of camera, the travelling condition of the lens stop release plate is different. Therefore, in the case when the lens is replaced by a different one, the accuracy in control will be lowered if the camera is such that the travelling of the lens stop release plate is abruptly changed.